For Democrats and Republicans fighting for control of the House, the official start of the general election begins Wednesday when the final primaries of the cycle are on the books.

The House landscape remains fluid as both parties and their allies strategize and begin to dump millions of dollars into the fall TV ad war that is ramping up post-national party conventions and Labor Day.

Both parties are poised to pick up seats in November, but how many and in what states will be determined by decisions made during the next eight weeks.

Almost halfway through September, this much is clear: A wave election appears highly unlikely. That means Democrats' chances of taking back control of the House remain slim as they fight district by district. But, given the seats in play right now, the minority party appears poised to net a handful of seats.

"It's going to be a very minor seat change, very little change across in the House," GOP pollster Glen Bolger said. "There's no massive movement. ... It's a seat-by-seat fight, and that generally means a low number net seat change."

Bolger said that unlike the partisan wave elections in 2006, 2008 and 2010, this year's November gains would be more on par with the modest net changes in the early part of the past decade, and he predicted "a seat-by-seat slog."

Democrats feel a little better about that path now though than they did a month ago. President Barack Obama's improving poll numbers and a series of events during the past few weeks have given top Democrats hope that this cycle might be better for their House candidates than they thought.

"I think that Democratic candidates and campaigns are showing a lot of promise," Democratic pollster Jef Pollock said, noting a series of recent nonpartisan polls have shown Democrats in swing districts in good shape. "Right now, it doesn't feel like a wave, it feels very individual, so these individual polls matters."

But Republicans push back that the landscape is mostly unchanged.

"I don't think that there have been any encouraging signs on the House of Representatives front for the Democrats in six months," GOP strategist Brad Todd said. "All the data I have seen in 50 districts indicates that Democrats are going to struggle to gain more than a couple of seats."

The Democratic Congressional Campaign Committee and the National Republican Congressional Committee have begun their independent expenditure spending in earnest, and both are, more or less, on offense. The DCCC IE has aired or is airing ads in 16 races, three-quarters of which are against Republican Members. The NRCC IE has aired or is airing ads in 21 districts, about half of them against Democratic incumbents. Many of the Republican ads launched this week.

Both parties have been working to expand the map of competitive races. The NRCC has been airing ads, for example, against Iowa Democratic Reps. Bruce Braley and Dave Loebsack, who have been considered in pretty comfortable shape to this point, especially Braley.

The DCCC has been pushing to expand its map in similar ways, leading DCCC Chairman Steve Israel (N.Y.) to remain confident the House is "absolutely in play."

Israel said August had been a good month for the party.

"I think we got our mojo back in August," he said in an interview with Roll Call last week.

The chairman cited three events he saw as moving the momentum behind his party. The first was GOP presidential nominee Mitt Romney's choice of Rep. Paul Ryan (Wis.) as his running mate, which he said helped to nationalize the debate about Medicare.

The second was Missouri GOP Senate nominee Rep. Todd Akin's comments about "legitimate rape." And the third was the revelation that some freshman House Members had gone swimming in the Sea of Galilee on an official trip to Israel last year - including one Member without his bathing suit.

Republicans deny Democrats have gotten any momentum at all in recent weeks, pointing to a still-troubled economic picture.

Republicans are right that the economy will weigh heavily in a lot of voters' minds. And Akin and the Holy Land skinny-dip trip are likely to fade into the noise of the broader campaign between now andNov. 6. But Ryan and his budget will remain front and center in campaigns across the country.

House Democrats "were going to do that communication anyway, but now they are going to get all of that help from above reinforcing the message," said John Anzalone, a top Democratic pollster.

For most competitive and just-might-be competitive House races, the air wars are just beginning. But a few battles have evolved more fully.

One example is North Carolina's 7th district, where Democratic Rep. Mike McIntyre faces a tough challenge from state Sen. David Rouzer. It's shaping up to be one of the more expensive races of the cycle. And in a sign of how fierce the fight already is, the House campaign committees have already spent more than $900,000 combined on the race. That figure doesn't include what the campaigns and third-party groups such as theDemocratic-aligned House Majority PAC have invested on TV in the race.

In a preview of how national messaging might play out in other competitive races, both House campaign committees have been working the Medicare issue hard.

How resonant each party's Medicare messaging ends up being with voters may well decide the outcome of competitive races. But especially in races such as McIntyre's, in districts that favor Republicans, if the GOP can simply neutralize the attacks about Medicare and pivot back to the economy and Obama, the path to the 113th Congress becomes steeper for the incumbent.

But it won't just be the committees and the campaigns that drive Congressional races. Super PACs, on both sides of the aisle, will play a strong role in determining the broad House landscape. "The only thing that keeps me up at night is the super PACs," Israel said. "They're like a Death Star, in a far corner of the universe waiting to vaporize or try and vaporize our candidates in specific districts."

He makes the argument that, unlike last cycle, when GOP super PACs hit a Democratic candidate, there will be Democratic-allied super PACs that can be "throwing punches back."

But perhaps more influential than even super PACs this cycle will be how the top of the ticket does. Post-conventions, Obama currently has an edge. That could boost Democrats in swing districts, but strategists of both parties cautioned that the election is still a political lifetime away.